Foodstuffs - Detection of irradiated food using photostimulated luminescence

This European Standard specifies a method for the detection of irradiated foods using photostimulated luminescence (PSL). The technique described here comprises an initial measurement of PSL intensity which may be used for screening purposes, and a calibration method to determine the PSL sensitivity to assist classification. It is necessary to confirm a positive screening result using calibrated PSL or another standardised (e.g. EN 1784 to EN 1788) or validated method.
The method has been successfully tested in interlaboratory trials using shellfish [1] and herbs, spices and seasonings. From other studies it may be concluded that the method is applicable to a large variety of foods [2], [3], [4], [5].

Lebensmittel - Nachweis von bestrahlten Lebensmitteln mit Photostimulierter Lumineszenz

Diese Europäische Norm legt ein Verfahren fest, das zum Nachweis einer Strahlenbehandlung von Lebensmitteln mit Photostimulierter Lumineszenz (PSL) geeignet ist. Das beschriebene Verfahren besteht aus einer Messung der ursprünglichen PSL-Intensität ("Screening") und einem Kalibrierverfahren zur Bestimmung der PSL-Empfind-lichkeit als Hilfe für die Klassifizierung. Es ist erforderlich, ein positives Ergebnis des Screening-Tests mit kali-brierter PSL oder einem anderen genormten (z. B. EN 1784 bis EN 1788) oder validierten Verfahren zu bestätigen.
Das Verfahren wurde in Ringversuchen erfolgreich an Krebs- und Weichtieren [1] sowie an Kräutern, Gewürzen und Gewürzzubereitungen validiert. Aufgrund weiterer Untersuchungen kann gefolgert werden, dass das Verfahren auf viele verschiedene Lebensmittel angewandt werden kann [2], [3], [4], [5].

Produits alimentaires - Détection d'aliments ionisés par photoluminescence

La présente Norme européenne décrit une méthode de détection des produits ayant subi un traitement ionisant, par analyse de luminescence photostimulée (PSL). La technique décrite ici comprend un mesurage initial de l'intensité de PSL qui peut être utilisée pour des besoins de criblage ainsi qu'une méthode d'étalonnage permettant de déterminer la sensibilité de la PSL et d'aider la classification des aliments analysés. Un résultat positif de criblage doit être confirmé à l'aide de la PSL étalonnée ou d'une autre méthode normalisée (par exemple, les EN 1784 à EN 1788) ou validée.
La méthode a été appliquée avec succès lors d'essais interlaboratoires conduits sur des crustacés [1] et des aromates, des épices et des condiments. D'autres études montrent que cette méthode est applicable à une grande variété d'aliments [2], [3], [4].

Živila - Detekcija obsevane hrane z uporabo fotostimulativne luminescence

General Information

Status
Withdrawn
Publication Date
17-Sep-2002
Withdrawal Date
14-Jul-2009
Current Stage
9960 - Withdrawal effective - Withdrawal
Due Date
15-Jul-2009
Completion Date
15-Jul-2009

RELATIONS

Buy Standard

Standard
EN 13751:2002
English language
11 pages
sale 10% off
Preview
sale 10% off
Preview
e-Library read for
1 day

Standards Content (sample)

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Živila - Detekcija obsevane hrane z uporabo fotostimulativne luminescenceLebensmittel - Nachweis von bestrahlten Lebensmitteln mit Photostimulierter LumineszenzProduits alimentaires - Détection d'aliments ionisés par photoluminescenceFoodstuffs - Detection of irradiated food using photostimulated luminescence67.050Splošne preskusne in analizne metode za živilske proizvodeGeneral methods of tests and analysis for food productsICS:Ta slovenski standard je istoveten z:EN 13751:2002SIST EN 13751:2002en01-november-2002SIST EN 13751:2002SLOVENSKI

STANDARD
SIST EN 13751:2002

EUROPEAN STANDARDNORME EUROPÉENNEEUROPÄISCHE NORMEN 13751September 2002ICS 67.050English versionFoodstuffs - Detection of irradiated food using photostimulatedluminescenceProduits alimentaires - Détection d'aliments ionisés parphotoluminescenceLebensmittel - Nachweis von bestrahlten Lebensmitteln mitPhotostimulierter LumineszenzThis European Standard was approved by CEN on 5 August 2002.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this EuropeanStandard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards may be obtained on application to the Management Centre or to any CEN member.This European Standard exists in three official versions (English, French, German). A version in any other language made by translationunder the responsibility of a CEN member into its own language and notified to the Management Centre has the same status as the officialversions.CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece,Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMITÉ EUROPÉEN DE NORMALISATIONEUROPÄISCHES KOMITEE FÜR NORMUNGManagement Centre: rue de Stassart, 36

B-1050 Brussels© 2002 CENAll rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 13751:2002 ESIST EN 13751:2002

EN 13751:2002 (E)2ContentspageForeword......................................................................................................................................................................31Scope..............................................................................................................................................................32Terms and definitions....................................................................................................................................33Principle..........................................................................................................................................................44Reagents.........................................................................................................................................................55Apparatus.......................................................................................................................................................56Sampling technique.......................................................................................................................................67Procedure.......................................................................................................................................................68Evaluation.......................................................................................................................................................79Limitations......................................................................................................................................................910Validation........................................................................................................................................................911Test report....................................................................................................................................................10Bibliography..............................................................................................................................................................11SIST EN 13751:2002

EN 13751:2002 (E)3ForewordThis document EN 13751:2002 has been prepared by Technical Committee CEN/TC 275 "Food analysis - Hori-zontal methods", the secretariat of which is held by DIN.This European Standard shall be given the status of a national standard, either by publication of an identical text orby endorsement, at the latest by March 2003, and conflicting national standards shall be withdrawn at the latest byMarch 2003.According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following coun-tries are bound to implement this European Standard: Austria, Belgium, Czech Republic, Denmark, Finland,France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Portugal, Spain, Swe-den, Switzerland and the United Kingdom.1 ScopeThis European Standard specifies a method for the detection of irradiated foods using photostimulated lumines-cence (PSL). The technique described here comprises an initial measurement of PSL intensity which may be usedfor screening purposes, and a calibration method to determine the PSL sensitivity to assist classification. It is nec-essary to confirm a positive screening result using calibrated PSL or another standardised (e.g. EN 1784 toEN 1788) or validated method.The method has been successfully tested in interlaboratory trials using shellfish and herbs, spices and seasonings[1]. From other studies it may be concluded that the method is applicable to a large variety of foods [2], [3], [4].2 Terms and definitionsFor the purposes of this European Standard, the following terms and definitions apply.2.1photostimulated luminescence (PSL)radiation specific phenomenon resulting from energy stored by trapped charge carriers. Release of this stored en-ergy by optical stimulation can result in a detectable luminescence signal.2.2PSL intensityamount of light detected during photostimulation, in photon count rate2.3screening PSL or initial PSLPSL intensity recorded from the sample as received or following preparation2.4calibrated PSLPSL intensity recorded from the test sample following irradiation to a known dose, after initial PSL measurement2.5thresholdsvalues of PSL intensity used for classification. In screening mode, two thresholds, a lower threshold (T1) and anupper threshold (T2) are used to classify the sampleSIST EN 13751:2002

EN 13751:2002 (E)42.6negative PSL resultPSL intensity below the lower threshold (less than T1)2.7intermediate PSL resultPSL intensity between the upper and the lower threshold (greater than or equal to T1, less than or equal to T2)2.8positive PSL resultPSL intensity above the upper threshold (greater than T2)2.9dark countphoton count rate from the photomultiplier with an empty chamber in the absence of stimulation2.10light countphoton count rate with a reference light source (e.g. 14C loaded scintillant, or equivalent) in the sample chamber2.11empty chamber runPSL intensity measured from an empty sample chamber to ensure absence of contamination of the chamber3 Principle3.1 GeneralMineral debris, typically silicates or bioinorganic materials such as calcite which originate from shells or exoskele-tons, or hydroxyapatite from bones or teeth, can be found on most foods. These materials store energy in chargecarriers trapped at structural, interstitial or impurity sites, when exposed to ionising radiation. Excitation spectros-copy has shown that optical stimulation of minerals releases charge carriers [5], [6], [7]. It has subsequently beenshown that the same spectra can be obtained from whole herb and spice samples and other foods usingphotostimulation [2], [8], [9]. PSL measurements do not destroy the sample, therefore whole samples, or othermixtures of organic and inorganic material, can be measured repeatedly. PSL signals, however, decrease if thesame sample is measured repeatedly.The methodology comprises screening (initial) PSL measurements to establish the status of the sample (see 2.3)and an optional second measurement following a calibration radiation dose to determine the PSL sensitivity of thesample (see 2.4).3.2 Screening PSLFor screening (see 2.3) the signal levels are compared with two thresholds (see 2.5). The majority of irradiatedsamples produce a strong signal above the upper threshold level. Signals below the lower threshold suggest thatthe sample has not been irradiated. Signal levels between the two thresholds, intermediate signals, show that fur-ther investigations are necessary. The use of thresholds produces an effective screening method which can also bebacked up by calibration, by TL as described in EN 1788 or another validated method, e.g. [3], [4], [8].3.3 Calibrated PSLFor calibration, the sample is exposed to a defined radiation dose after the initial PSL measurement, and then re-measured. Irradiated samples show only a small increase in PSL after this radiation exposure, whereas unirradi-ated samples usually show a substantial increase in PSL signal after irradiation.SIST EN 13751:2002

EN 13751:2002 (E)54 Reagents4.1 Aerosol silicone grease,e.g. Electrolube SC0200H1)4.2 Water,deionized5 Apparatus5.1 PSL system,e.g. SURRC PPSL Irradiated food screening system1) [10], [11], [12], [13] comprising samplechamber, stimulation source, pulsed stimulation and synchronised photon counting system. For instrumental set-up, see 7.4.NOTEFor the interlaboratory tests, the SURRC PPSL system has been used.5.2 Disposable Petri-dishesNOTEFor the interlaboratory tests, 5 cm Petri-dishes have been used.5.3 Radiation source,capable of irradiating samples with a defined radiation dose before measurement ofcalibrated PSL. In the interlaboratory tests on shellfish and herbs, spices and their mixtures [1], sources delivering60Co-rays have been employed at a fixed radiation dose of 1 kGy.Alternative sources may be used providing they have been found satisfactory.NOTEOther fixed doses can be suitable.5.4 14C-Source(optional)5.5 Laminar flow cabinet(optional)5.6 Air duster(optional)6 Sampling techniqueWhenever possible, the sample is taken from a light-protected position in the food consignment, since the PSL in-tensity decreases on exposure to light.Before analysis, samples should be protected against light exposure. Store them in the dark.7 Procedure7.1 GeneralAll dispensing and handling of samples should be carried out under subdued lighting whenever possible. Samplesare dispensed into disposable Petri-dishes and introduced to the system.

1)Electrolube SC0200H and Scottish Universities Research and Reactor Center Pulsed Photostimulated Luminescence(SURRC PPSL) are examples of products available commercially. This information is given for the convenience of users of thisstandard and does not constitute an endorsement of CEN of these products. Equivalent products may be used if they can beshown to lead to equivalent results.SIST EN 13751:2002

EN 13751:2002 (E)6Samples should be handled with care to avoid cross-contamination during dispensing. It is recommended thatsamples are dispensed individually, under a laminar flow cabinet (5.5), and fresh tissue is placed on the bench foreach sample. The Petri-dish should be covered with a lid to reduce the possibility of contamination.7.2 Preparation of herb, spice and seasoning samplesSamples are dispensed into clean Petri-dishes, in duplicate. If these test samples lead to inconsistent classifica-tions, a further four aliquots shall be dispensed and classification based on the highest two results. Some samplesmay require a minimum of preparation; e.g. vanilla pods may need to be cut to fit the dish and wrappings should beremoved.Samples can either be dispensed in a thick layer within the Petri-dish or in a thin layer, applied to a dish alreadysprayed with silicone grease (4.1) to fix the sample. Thicker layer samples are less likely to be affected by bleach-ing; subsurface minerals can be exposed by gentle agitation.NOTEThin layer samples can also be dispensed into planchets or other shallow containers suitable for irradiation with90Sr or other sources. If a gamma source is used for calibration either dispensing method is suitable.7.3 Preparation of shellfish7.3.1 GeneralPSL analysis can be conducted using whole samples including shell, shelled whole samples and dissected intes-tines or minerals extracted by flushing with water (4.2).If enough sample material is available, it is recommended that samples be divided into at least six portions, i.e. sixPetri-dishes.7.3.2 Whole samplesWhole samples including shell can be placed as received in the Petri-dish. In some cases it may be necessary tocut the shellfish to fit the Petri-dish. If the intestinal tract is visible, it is preferable to place this uppermost.7.3.3 Shelled whole samplesShelled whole samples can be placed whole in the Petri-dish, again with the intestinal tract facing upwards, usingas many individual shellfish as will fit in the Petri-dish.7.3.4 Shellfish intestinesShellfish intestines can be found as a thin dark tube on the convex side of prawns or shrimps, and in the interiors ofmolluscs. Using a scalpel, slice the flesh open and with tweezers remove the intestinal tract. Repeat this techniqueon several samples of shellfish (recommended: 6 intestines per Petri-dish).7.4 Instrumental Set-UpThis section describes the set-up of the SURRC PPSL system, as an example.The system is used in conjunction with a computer for setting individual measurement parameters (cycle time,thresholds and data recording conditions) for recording quantitative photon counts.NOTE 1The system can be used in a stand-alone mode, with simple push button controls, for preliminary measurements.However, the validated procedures which are the subject of this standard apply only to quantitative measurements performed inconjunction with a computer.The instrumental set-up procedure includes checks on dark count (2.9) and light count (2.10), establishing meas-urement parameters and checks on irradiated and unirradiated standard materials.SIST EN 13751:2002

EN 13751:2002 (E)7For herbs and spices tested in the interlaboratory trial [1], the

...

Questions, Comments and Discussion

Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.